Known in the prior art are devices for liquid cooling of rotor winding, using forced liquid supply, where a liquid flow is forced through the hollow conductors of the winding by a pump.
The devices for rotor winding liquid cooling with a forced liquid supply suffer from the following disadvantages:
axial channels are required in the rotor shaft to supply the liquid, the liquid supply channels hampering the current supply to the rotor winding which is also accomplished through the axial channels provided in the rotor shaft;
an anticorrosive protection of the surface of liquid supply channels is required;
a mechanical coupling is required between the rotor shaft and the winding via a water-conducting means. Such a mechanical coupling produces alternating forces in the water-conducting means due to a difference in stiffnesses of the rotor body and the rotor shaft tail portion, this decreasing the reliability of the water-conducting means;
a high pressure (up to 200 kg/cm.sup.2) of the cooling liquid in winding channels, reducing the reliability of soldered joints in the winding.
Free from the above-mentioned disadvantages are rotor winding liquid cooling devices using a self-pumping liquid cooling system.
The self-pumping liquid cooling devices for rotor winding are known wherein the liquid circulates through the winding due to a centrifugal head generated in the rotating rotor because of a difference between the radial levels of the supplied and collected liquid.
Known also in the prior art are self-pumping liquid cooling devices for rotor winding, comprising a means for supplying the cooling liquid to the rotor winding and a means for collecting the cooling liquid. The latter is formed by an external cylindrical member fastened to the rotor and by a stationary internal cylindrical member, both members being arranged concentrically with the shaft. The cooling liquid collecting chamber is disposed in the clearance between the external and internal cylindrical members (cf. USSR Author's Certificate No. 236610, Cl. H02K 9/193, 1969).
The disadvantage of this device consists in that the cooling liquid is discharged unobjected from the external cylindrical member rotating with the rotor into a stationary collecting chamber, the cooling liquid discharged at a high speed being strongly splashed, which hampers a reliable sealing of the chamber from the internal cavity of the stator. In addition, an excessive pressure produced in the collecting chamber by rotating rotor members which pump air into the liquid collecting chamber, thus not allowing to provide a reliable sealing of the chamber from the internal cavity of the stator and reducing the reliability of the electric machine.
Partially free from the above-mentioned disadvantage is the device for liquid cooling of rotor winding of an electric machine, specifically a turbo-generator, with a self-pumping liquid cooling system, comprising a means for supplying the cooling liquid into the rotor winding and a means for collecting the cooling liquid. The latter is formed by an external cylindrical member having an annular recess on its internal surface and fastened to the rotor, and by a stationary internal cylindrical member, both members being arranged concentrically relative to the shaft. On the winding side of the external surface of the internal cylindrical member an annular projection is formed, extending into the annular recess made on the internal surface of the external cylindrical member. As the device operates, the annular projection of the internal cylindrical member and the annular recess of the external cylindrical member form a hydraulic seal protecting the liquid collecting chamber against the penetration of air that can be drawn by liquid splashes into the internal space of electric machine stator via the labyrinth packing, which cannot be tolerated. The cooling liquid collecting chamber is disposed in the clearance between the external and internal cylindrical members behind the annular projection, on the side opposite to the rotor winding (cf. USSR Author's Certificate No. 253,219, Cl. H02K, 1969).
The disadvantage of the device described hereinabove is a free discharge of the cooling liquid from the external cylindrical member rotating with the rotor into the stationary liquid collecting chamber, which is accompanied by a strong splashing of the cooling liquid discharged into the liquid collecting chamber at a high speed, thus hampering a reliable sealing of this chamber from the internal cavity of the stator and reducing the reliability of the electric machine, since the liquid can penetrate into the internal space of the stator.